APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

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APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by APOD Robot » Tue May 13, 2014 4:05 am

Image CG4: A Ruptured Cometary Globule

Explanation: Can a gas cloud grab a galaxy? It's not even close. The "claw" of this odd looking "creature" in the above photo is a gas cloud known as a cometary globule. This globule, however, has ruptured. Cometary globules are typically characterized by dusty heads and elongated tails. These features cause cometary globules to have visual similarities to comets, but in reality they are very much different. Globules are frequently the birthplaces of stars, and many show very young stars in their heads. The reason for the rupture in the head of this object is not completely known. The galaxy to the left of the globule is huge, very far in the distance, and only placed near CG4 by chance superposition.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by starsurfer » Tue May 13, 2014 10:09 am

Jason Jennings has been long overdue for an APOD for many years now! Magnificent image of one of the strangest areas of the southern sky. I believe the first major image of this was the AAO image by David Malin. The full frame of this image is incredible showing many more dust clouds and another galaxy. The only criticism about the full image is it isn't oriented north up like it is in this APOD.

Like many other cometary globules in Puppis, it is associated with the giant Gum Nebula. One of the very few if not only that shows this in a wider context is this amazing widefield by Marco Lorenzi.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Nitpicker » Tue May 13, 2014 11:01 am

starsurfer wrote:Jason Jennings has been long overdue for an APOD for many years now! Magnificent image of one of the strangest areas of the southern sky. I believe the first major image of this was the AAO image by David Malin. The full frame of this image is incredible showing many more dust clouds and another galaxy. The only criticism about the full image is it isn't oriented north up like it is in this APOD.
Galactic North is up (more or less) in the full frame APOD, as it was when originally published. It is also orientated (more or less) as one observes it relative to the horizon on an April evening (when captured). I think anyone who can produce an image like this has earned the right to rotate it however they like. (I might baulk at a mirror image, but we all have our issues.)

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Boomer12k » Tue May 13, 2014 11:04 am

Interesting....

Looks like a pussycat, playing on its back....

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Psnarf » Tue May 13, 2014 1:30 pm

Is not that the thing into which Commodore Decker piloted the U.S.S. Constellation?

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Brian Sherwood » Tue May 13, 2014 1:37 pm

Is that a circular asterism off of the end of the galaxy being show "near" the nebula, or perhaps a gravity lens artifact?

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Leo Bellantoni » Tue May 13, 2014 1:38 pm

To the left and below CG4 in this image are an improbable looking number of stars arranged in arcs, and in one case a complete circle. Is there some gravitational lensing going on here?

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Chris Peterson » Tue May 13, 2014 2:02 pm

Leo Bellantoni wrote:To the left and below CG4 in this image are an improbable looking number of stars arranged in arcs, and in one case a complete circle. Is there some gravitational lensing going on here?
The same thing is seen in all rich star fields. It is because our brains seek such patterns.

Gravity lensing is the result of very distant objects being distorted by nearer galaxies or galaxy clusters. Gravity lensing doesn't produce point images.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Leon M. Green » Tue May 13, 2014 2:20 pm

Why wasn't the galaxy to the left named/numbered instead of just mentioned? One would also like to explore that. Thanks.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Chris Peterson » Tue May 13, 2014 2:26 pm

Leon M. Green wrote:Why wasn't the galaxy to the left named/numbered instead of just mentioned? One would also like to explore that. Thanks.
There are millions of galaxies like that all over the sky. It may or may not have been cataloged. If so, it's probably just a number in a list somewhere. Most such objects have never received any directed attention at all.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by geckzilla » Tue May 13, 2014 2:37 pm

Chris Peterson wrote:
Leon M. Green wrote:Why wasn't the galaxy to the left named/numbered instead of just mentioned? One would also like to explore that. Thanks.
There are millions of galaxies like that all over the sky. It may or may not have been cataloged. If so, it's probably just a number in a list somewhere. Most such objects have never received any directed attention at all.
It's catalogued as ESO 257-19 (among a few other things) in SIMBAD.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by owlice » Tue May 13, 2014 3:01 pm

starsurfer wrote:Jason Jennings has been long overdue for an APOD for many years now!
APOD is not a contest, however much some people want to think it is, and no one is "due" an APOD. That stupid notion needs to die; please do not resuscitate it. Thanks.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Chris Peterson » Tue May 13, 2014 3:04 pm

geckzilla wrote:It's catalogued as ESO 257-19 (among a few other things) in SIMBAD.
I'm not surprised, given the proliferation of deep, fast surveys in recent years. I note that every published reference to this object is some sort of survey, catalog, or statistical study. Nobody has looked at it closely because of some unusual characteristic. It's just another face in the crowd.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by geckzilla » Tue May 13, 2014 3:28 pm

Yup. I'm just happy when they get something with less than 7 numbers in them. The 2MAS and IRAS designations are useful in lieu of anything else but it sure is clumsy to write about them. For example, there is apparently another tiny galaxy behind ESO 257-19... It's called 6dFGS gJ073507.6-465543 (also part of a survey, of course.)
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Ron-Astro Pharmacist » Tue May 13, 2014 5:13 pm

The link to "dusty" caught my eye and, upon reading, it was very thought provoking. Interstellar dust appears to be quite the stuff. It seems conceivable that through gravitational rotation and random interactions that helical structures could evolve. Anyone know how much the idea has been investigated as the stuff of life?

http://www.space.com/13401-cosmic-star- ... ounds.html

Obviously some have but others may have refuted the concept scientifically. We had some interesting beginning but I might gravitate to give it my vote as "Most Desirable". At least given the choice philosophically over Earth-based hypotheses as it might mean life could be prevalent thus more likely discovered in my lifetime. That would also get my vote.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Chris Peterson » Tue May 13, 2014 5:20 pm

Ron-Astro Pharmacist wrote:The link to "dusty" caught my eye and, upon reading, it was very thought provoking. Interstellar dust appears to be quite the stuff. It seems conceivable that through gravitational rotation and random interactions that helical structures could evolve. Anyone know how much the idea has been investigated as the stuff of life?
We have no observational evidence I'm aware of for gravitationally created helical structures. There may be helical structures associated with very energetic events like novas and supernovas, as well as within jets. But not in gravity dominated dust clouds.

At the molecular scale, gravity is not a factor at all. The shapes of molecular structures are dictated by electromagnetic forces.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Mactavish » Tue May 13, 2014 5:35 pm

owlice wrote:
starsurfer wrote:Jason Jennings has been long overdue for an APOD for many years now!
APOD is not a contest, however much some people want to think it is, and no one is "due" an APOD. That stupid notion needs to die; please do not resuscitate it. Thanks.
Okay, you made your point. I don’t believe, though, that Starsurfer considers APOD to be a contest. Rather, he pays a well-deserved compliment to Jennings. I see nothing in his comment that is “stupid.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by owlice » Tue May 13, 2014 5:48 pm

Mactavish, it's a gorgeous image -- no doubt about that -- but to say that someone, anyone, has been "long overdue" for something which no one is "due" is nonsensical.

If you wish to discuss this further, PM me. Thanks.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by starsurfer » Wed May 14, 2014 9:08 pm

Nitpicker wrote:
starsurfer wrote:Jason Jennings has been long overdue for an APOD for many years now! Magnificent image of one of the strangest areas of the southern sky. I believe the first major image of this was the AAO image by David Malin. The full frame of this image is incredible showing many more dust clouds and another galaxy. The only criticism about the full image is it isn't oriented north up like it is in this APOD.
Galactic North is up (more or less) in the full frame APOD, as it was when originally published. It is also orientated (more or less) as one observes it relative to the horizon on an April evening (when captured). I think anyone who can produce an image like this has earned the right to rotate it however they like. (I might baulk at a mirror image, but we all have our issues.)
I meant that the full image on the original website isn't north up. Just as Ann is a colour commentator, I'm an orientation commentator.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by starsurfer » Wed May 14, 2014 9:09 pm

owlice wrote:
starsurfer wrote:Jason Jennings has been long overdue for an APOD for many years now!
APOD is not a contest, however much some people want to think it is, and no one is "due" an APOD. That stupid notion needs to die; please do not resuscitate it. Thanks.
It was just a bad choice of words, I was really overexcited! :D

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Nitpicker » Wed May 14, 2014 9:17 pm

starsurfer wrote:
Nitpicker wrote:
starsurfer wrote:Jason Jennings has been long overdue for an APOD for many years now! Magnificent image of one of the strangest areas of the southern sky. I believe the first major image of this was the AAO image by David Malin. The full frame of this image is incredible showing many more dust clouds and another galaxy. The only criticism about the full image is it isn't oriented north up like it is in this APOD.
Galactic North is up (more or less) in the full frame APOD, as it was when originally published. It is also orientated (more or less) as one observes it relative to the horizon on an April evening (when captured). I think anyone who can produce an image like this has earned the right to rotate it however they like. (I might baulk at a mirror image, but we all have our issues.)
I meant that the full image on the original website isn't north up. Just as Ann is a colour commentator, I'm an orientation commentator.
And I'm a nitpicker and Galactic North is different from Celestial North. Galactic North is up (more or less) in the full frame APOD, as it was when originally published on Jason Jennings' website.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Beyond » Wed May 14, 2014 9:43 pm

Nitpicker wrote:And I'm a nitpicker and Galactic North is different from Celestial North. Galactic North is up (more or less) in the full frame APOD, as it was when originally published on Jason Jennings' website.
And a very good picker of nits you are! In brightest day, in darkest night, no un-picked nit shall escape your sight.
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Nitpicker » Thu May 15, 2014 12:00 am

Another little factoid I read the other day, is that an early convention of map making was to show East up, and that this was the origin of the term "orientation" ... East = Orient.

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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by Beyond » Thu May 15, 2014 12:13 am

See what I mean?? :lol2:
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Re: APOD: CG4: A Ruptured Cometary Globule (2014 May 13)

Post by starsurfer » Thu May 15, 2014 10:42 am

Nitpicker wrote:
starsurfer wrote:
Nitpicker wrote:
Galactic North is up (more or less) in the full frame APOD, as it was when originally published. It is also orientated (more or less) as one observes it relative to the horizon on an April evening (when captured). I think anyone who can produce an image like this has earned the right to rotate it however they like. (I might baulk at a mirror image, but we all have our issues.)
I meant that the full image on the original website isn't north up. Just as Ann is a colour commentator, I'm an orientation commentator.
And I'm a nitpicker and Galactic North is different from Celestial North. Galactic North is up (more or less) in the full frame APOD, as it was when originally published on Jason Jennings' website.
I was talking about celestial north! Also the orientation of the image on APOD and then on Jason Jennings website is different. This discussion has been wonderful! Now I have some idea of what Ann feels when she commentates on colour. What a wonderful and brilliant community this is! Group hug everyone! :D